feat(FN-1163): align command references with fn naming

- Update CLI command strings, help text, and project-resolution messaging to reference fn
- Sync core backup/store messaging and dashboard API/planning/subtask prompt examples with fn usage
- Refresh dashboard UI copy in settings, project detection, and PR guidance for consistent command naming
- Adjust CLI/dashboard tests and add a @gsxdsm/fusion changeset for the naming alignment patch

packages/cli/src/__tests__/extension.test.ts

@@ -57,7 +57,7 @@ function makeCtx(cwd: string) {
 
 // ── Tests ──────────────────────────────────────────────────────────
 
-describe("kb pi extension", () => {
+describe("fn pi extension", () => {
   let tmpDir: string;
   let api: ReturnType<typeof createMockAPI>;